Compression encoding of video signals is widely used. In at least some of the most common compression encoding standards, such as MPEG-2 and MPEG-4, fields or frames of video signals are divided into blocks of pixels (8×8) for coding purposes. A disadvantage of such compression-encoding schemes is that blocking artifacts may be produced upon recovery (decoding) of the video signal. Various proposals have been made for blocking artifact reduction after decoding of compression-encoded video signals, but such proposals have assumed that the positioning and size of the block grid relative to the image plane is known. However, if side information from the decoder about the block grid is not available, the size of blocks and the offset of the grid, if any, may not be known to the blocking artifact reduction function. As a result, satisfactory blocking artifact reduction may not occur.